George l



(N0 Medal.) T a G. L. BALL.

ELEGTRIGAL SAFETY SWITCH.

Patented May 26, 1891..

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. combinations PATENv @FFICE.

GEORGE L. HALL, OF LOWELL, MASSA( lll'filil'lTfi.

ELECTRICAL SAFETY-SWHTCH.

SPECIFICATION forming part of Letters Patent No. d53,046, dated May 26, 1891. Application filed March 19, 1890. serial in 344,452. on model-l T 0 aZZ whom it may concern:

Be it known that I,- GEORGE L. HALL, a citizen of the United States, residing at Lowell, in the county of 'Middlesex and Common= wealth of Massachusetts, have invented a certain new and useful Improvement in Electrieal Satety-Switehes,of which the following is a specification. 7

My invention relates to electrical safety switches; and it consists'in the devices and hereinafter described and claimed, the object of the same being to open the line in one or more places, preferably two, upon a failure of the current, as by the breakage of the line-wire, and to prevent accidents which might be caused by the falling of a broken -end of the line-wire upon a person or animal, or upon other conducting material electrically connected with the earth.

In the accompanying drawings, Figure 1 is an isometric perspective view of my improved safety-switch arranged in a'line containinga dynamo and electric-arc lights, showing also an alarm bell circuit normally open and adapted to be closed by the operation of the switch to give an alarm to an attendant in the dynamooroom, the safety-switch being closed; Fig. 2, a frontclevation'of said safetyswitch open, the alarm devices the main line, dynamo, and lights being omitted and the alarm-circuit being closed; Fig. 3, a side el e= vation of one of the switell-supporting brack= cts, the upper portion of the same being in central vertical section to show the levers ofa pair insulated from each other.

A represents so much of a dynamo as is necessary for the nndorstandingof my invention, a being the (3011111111tittOl-Sl1tfl3,'(t the commutator, and a and of the brushes of said dynamo, the parts being of any usual construction.

L. represents the line connecting the opposite brushesot the dynamo, and O are are lights arranged in the circuit in the usual The safety-switch hereinafter describedis arranged in the circuit, and consists of an electro-magn'et M, through which the current passes from the dynamo into a leverlof metal, thence into-a lever I normally in contact with the lover P, thence through the lightC,

' thence through a lever N and thence through to the bracket Q.

the lever N to the brush a of the dynamo. The

magnet from its armature m to be varied as may be desirable. The levers P N are connected to opposite brushes of the circuit, as shown in Fig. 1, and are of conducting material, as brass or copper, and areboth pivoted upon a bracket Q, having a vertical slot q, through which screws (1 are driven into the wall of the dynamo-roonnthe slot'enabling the bracket (,2 to be adjusted vertically to var the distance between the electro-magnet and its armature, as above stated. The armature n of the electro-magnet M is rigidly se- ClllGtL to one of the levers P N, to which one of them is immaterial, and said levers are rigidly connected to each other by cross-bars R R of insulating material, as vuloanite, so that said levers moveas one. The bearings of the levers P N are insulated from each otheneach of said levers being provided with a sleeve 1) and 'n,which turns upon a sleeve of insulating material, as hard rubber of, supported upon a 1'od'q,l1eld in cars g 1 which project upward from the bracket Q, as shown in Figs. 1 and 3 lVhena current is in. the line, the le vers P are held up in a horizontal position by the attraction of the electro-magnet M. The levers l N, also or? conducting material, are supported upon the bracketQ, just as the levers I)? are supported upon the bracket Q, their bearings being insulated from each other by an insulating-sleeve supported upon a rod held in cars q q on said bracket Q, and said last-named bracket is also adjustable upon the wall of a dvnamo-room or other support by means of a vertical slot qi and screws (1 corresponding to the parts ot the same name above described in referring The levers N P are not.

connected to each other mechanii'ially, but each is allowed to move independently of the other, in order to insure a better contact of these levers and. thclevers P N, the free end of the lever I" normally resting upon the free end of the lever l and the free end of the lever N upon the free end of the lever N when the switch is closed. The levers P N are connected bythe line L through the arc-light system, as shown in Fig. 1.

, rent, although not totally failing, is partially interrupted, producing what is called flashing of the lights, and it would be undesirable to open the circuit, because of such par- ,tial or momentary interruption. Ilhe crossbar R, which connects the levers P N near their free ends, is therefore connected by a link (I to the piston-rod d of a dash-pot D, the upper end of said link being pivoted at d to a bracket dtsecured on said cross-bar R, as shown in Fig. 2, and the lower end of said link being pivoted at d between ears d, with which the upper end of said piston-rod is provided, said dash-potD being constructed in the usual manner and partially filled with any suitable liquid, as glycerine, which resists the movement of the piston secured to the lower end of said piston-rod, and partially filling said dash-pot in a well-known manner. The dash-pot I), connected as above described to said levers I N, prevents their falling suddenly during a partial or momentary interruption of the current, and thus putting out all. the lights unnecessarily, and for the same reason the lovers 1 N overlie the levers I N, respectively, for a considerable distance. The meet the dash-pot allows the current to circulate for a short time, perhaps about a second or less, and enables the electro-magnet M to restore the levers .to their proper position if the current be immediately reestablished in full force.

The alarm devices consist of an electric bell E of the usual construction (either a tapbell or a buzz-bell) arranged in a short line I, containin g a battery B and a spring-switch S, consisting of two spring-terminals s 5', normally held apart by their own elasticity,but forced together by an arm d projecting horizontally from the piston-rod of the dash-pot, striking the upper terminal 8 and forcing it downward into contact with the terminal 5 when the levers P N fall to open the electriclight circuit, as above described. The signal-' bell will call the attention of an attendantin the dynamo-room to the fact that the line is opened and enable'iminediate attention to be given to repairing the line. After the line is restored to preper condition the switch 1 N N Pis closed by raising the dash-pot rod by means of the arm at, thus lifting the lever l N against the under sides of the levers 1 N, the latter being prevented by a projection q, extending into the path of said last-named levers from the bracket Q, from falling out of the arcdescribed by said levers l N when the latter are raised.

I claim as my invention- 1. The combination, in aclosed electric circuit, of a movable double switch consisting of two movable switches, one arranged in the I line out and the other in the line in, said switches being insulated from eaclfother but mechanically connected to each other, an electro-maguet arranged in the same circuit, and its armature secured to one of said switches, said magnet being arranged to hold said switches closed when the current is uninter-' rupted and at other times to allowsaid switches to be opened and the circuit to be broken in two places, as and for the. purpose specified.

2. The combination, in-a closed circuit, of a switch consisting of two levers, the free end of one of said levers overlapping and resting upon the free end of the other of said levers, an electro-magnet in said circuit, and its armature secured to the last-named lever to hold said lovers in contact while the current is uninterrupted, said levers upon an inter- .ruption of the currentbeing adapted to fall and separate from each other, as and for the purpose specified.

3. The combination, in a closed electric air cuit, of a switch consisting of two levers, the free end of one of said levers overlapping and resting upon the free end of the other of said levers, an-electro-magn'et in said circuit, its armature secured to the last-named lever to hold said levers in contact while the current is uninterrupted, said levers upon an interruption of the current being adapted to fall and separate from each other, and-means, substantially as described,- for retarding the falling of said levers in order that said switclr levers may not be separated bya momentary failure of the current and may be restored to position by the attraction of said magnet, as and for the purpose specified.

4. The combination, in a closed electric circuit, of a switch consisting of two lovers, the free end of one ofsaid levers overlapping and resting upon the free end of the other of said levers, an electromagnet in said circuit, its armature secured to the supporting-lever, a dash-pot cylinder, its piston and piston-rod,

said piston-rod being jointed to said supporting-lever to retard the falling of said levers and to prevent the instantaneous opening of said switch upon a momentary failure of the current and to enable said levers to be restored to position by the attraction of said magnet, as and for the purpose specified.

5. The combination, in a closed electric cir cuit, of a movable switch, an armature secured thereto, an electro-magnct in said circuit arranged to attract said armature and to hold said switch closed when the current is uninterrupted and at other times to allow said switch to be opened, anoth'er circuit arranged to be closed by the opening of said switch, and alarm devices arranged in said last--named circuit and operated upon the closing thereof, as and for the purpose specified. I

(3. The combination, ina closed electric circuit, of a switch consisting of two levers, the whereby restoring said supporting-lever to free end of one of said levers overlapping and position will also restore said overlapping leresting upon the free end of the other ofsaid ver to position, as and for the purpose specilevers,-an electro-magnet in said circuit, its fied. r 5

armature secured to the supporting-lever to In witness whereof I have signed this speciholdsaid levers in contact while the curfication, in the presence of two attesting wit-- rent is uninterrupted, said levers upon an innesses, this 25th dayof February, A. D. 1890.

terrupti'on ofthe current being adapted to GEORGE L. IIALL. fall and separate from each other, and a stop \Vitnesses: to prevent said overlapping lever from fall- ALBERT M. MOORE,

ing out of the arc of itssupporting-lever, MYRTIE G. BEALS. 

